Re: [dpdk-dev] [PATCH] eal: allow hugetlbfs sub-directories

[John Levon <john.levon@nutanix.com>]

On Mon, Aug 09, 2021 at 12:24:34PM +0100, John Levon wrote:

> get_hugepage_dir() was implemented in such a way that a --huge-dir
> option had to exactly match the mountpoint, but there's no reason for
> this restriction: DPDK might not be the only user of hugepages, and
> shouldn't assume it owns an entire mountpoint. For example, if I have
> /dev/hugepages/myapp, and /dev/hugepages/dpdk, I should be able to
> specify:
> 
> --huge-dir=/dev/hugepages/dpdk/
> 
> and have DPDK only use that sub-directory.
> 
> Fix the implementation to allow a sub-directory within a suitable
> hugetlbfs mountpoint to be specified, preferring the closest match.
> 
> Signed-off-by: John Levon <john.levon@nutanix.com>
> ---
> v2: prefer closer matches
> v3: checkpatch fixes
> v4: fix docs, added tests

Anyone like to (re) review?

thanks
john

> 
>  app/test/test_eal_flags.c                     | 116 ++++++++++++------
>  doc/guides/linux_gsg/linux_eal_parameters.rst |   3 +-
>  lib/eal/linux/eal_hugepage_info.c             |  83 +++++++++----
>  3 files changed, 138 insertions(+), 64 deletions(-)
> 
> diff --git a/app/test/test_eal_flags.c b/app/test/test_eal_flags.c
> index b4880ee802..1d18a0ba8f 100644
> --- a/app/test/test_eal_flags.c
> +++ b/app/test/test_eal_flags.c
> @@ -14,8 +14,9 @@
>  #include <errno.h>
>  #include <unistd.h>
>  #include <dirent.h>
> -#include <sys/wait.h>
>  #include <sys/file.h>
> +#include <sys/stat.h>
> +#include <sys/wait.h>
>  #include <limits.h>
>  #include <fcntl.h>
>  
> @@ -800,6 +801,9 @@ static int
>  test_misc_flags(void)
>  {
>  	char hugepath[PATH_MAX] = {0};
> +	char hugepath_dir[PATH_MAX] = {0};
> +	char hugepath_dir2[PATH_MAX] = {0};
> +	char hugepath_dir3[PATH_MAX] = {0};
>  #ifdef RTE_EXEC_ENV_FREEBSD
>  	/* BSD target doesn't support prefixes at this point */
>  	const char * prefix = "";
> @@ -810,6 +814,7 @@ test_misc_flags(void)
>  	FILE * hugedir_handle = NULL;
>  	char line[PATH_MAX] = {0};
>  	unsigned i, isempty = 1;
> +
>  	if (get_current_prefix(tmp, sizeof(tmp)) == NULL) {
>  		printf("Error - unable to get current prefix!\n");
>  		return -1;
> @@ -849,6 +854,20 @@ test_misc_flags(void)
>  	}
>  #endif
>  
> +	snprintf(hugepath_dir, sizeof(hugepath_dir), "%s/dpdk.missing", hugepath);
> +	snprintf(hugepath_dir2, sizeof(hugepath_dir2), "%s/dpdk.dir", hugepath);
> +
> +	if (mkdir(hugepath_dir2, 0700) != 0 && errno != EEXIST) {
> +		printf("Error - failed to mkdir(%s)\n", hugepath_dir2);
> +		return -1;
> +	}
> +
> +	snprintf(hugepath_dir3, sizeof(hugepath_dir3), "%s/dpdk.dir/sub", hugepath);
> +
> +	if (mkdir(hugepath_dir3, 0700) != 0 && errno != EEXIST) {
> +		printf("Error - failed to mkdir(%s)\n", hugepath_dir3);
> +		goto fail;
> +	}
>  
>  	/* check that some general flags don't prevent things from working.
>  	 * All cases, apart from the first, app should run.
> @@ -881,60 +900,66 @@ test_misc_flags(void)
>  	/* With invalid --huge-dir */
>  	const char *argv9[] = {prgname, "-m", DEFAULT_MEM_SIZE,
>  			"--file-prefix=hugedir", "--huge-dir", "invalid"};
> +	/* With invalid --huge-dir sub-directory */
> +	const char *argv10[] = {prgname, "-m", DEFAULT_MEM_SIZE,
> +			"--file-prefix=hugedir", "--huge-dir", hugepath_dir};
> +	/* With valid --huge-dir sub-directory */
> +	const char *argv11[] = {prgname, "-m", DEFAULT_MEM_SIZE,
> +			"--file-prefix=hugedir", "--huge-dir", hugepath_dir2};
>  	/* Secondary process with invalid --huge-dir (should run as flag has no
>  	 * effect on secondary processes) */
> -	const char *argv10[] = {prgname, prefix, mp_flag,
> +	const char *argv12[] = {prgname, prefix, mp_flag,
>  			"--huge-dir", "invalid"};
>  
>  	/* try running with base-virtaddr param */
> -	const char *argv11[] = {prgname, "--file-prefix=virtaddr",
> +	const char *argv13[] = {prgname, "--file-prefix=virtaddr",
>  			"--base-virtaddr=0x12345678"};
>  
>  	/* try running with --vfio-intr INTx flag */
> -	const char *argv12[] = {prgname, "--file-prefix=intr",
> +	const char *argv14[] = {prgname, "--file-prefix=intr",
>  			"--vfio-intr=legacy"};
>  
>  	/* try running with --vfio-intr MSI flag */
> -	const char *argv13[] = {prgname, "--file-prefix=intr",
> +	const char *argv15[] = {prgname, "--file-prefix=intr",
>  			"--vfio-intr=msi"};
>  
>  	/* try running with --vfio-intr MSI-X flag */
> -	const char *argv14[] = {prgname, "--file-prefix=intr",
> +	const char *argv16[] = {prgname, "--file-prefix=intr",
>  			"--vfio-intr=msix"};
>  
>  	/* try running with --vfio-intr invalid flag */
> -	const char *argv15[] = {prgname, "--file-prefix=intr",
> +	const char *argv17[] = {prgname, "--file-prefix=intr",
>  			"--vfio-intr=invalid"};
>  
>  	/* With process type as auto-detect */
> -	const char * const argv16[] = {prgname, "--file-prefix=auto",
> +	const char * const argv18[] = {prgname, "--file-prefix=auto",
>  			"--proc-type=auto"};
>  
>  	/* With process type as auto-detect with no-shconf */
> -	const char * const argv17[] = {prgname, "--proc-type=auto",
> +	const char * const argv19[] = {prgname, "--proc-type=auto",
>  			no_shconf, nosh_prefix, no_huge};
>  
>  	/* With process type as --create-uio-dev flag */
> -	const char * const argv18[] = {prgname, "--file-prefix=uiodev",
> +	const char * const argv20[] = {prgname, "--file-prefix=uiodev",
>  			"--create-uio-dev"};
>  
>  	/* run all tests also applicable to FreeBSD first */
>  
>  	if (launch_proc(argv0) == 0) {
>  		printf("Error - process ran ok with invalid flag\n");
> -		return -1;
> +		goto fail;
>  	}
>  	if (launch_proc(argv1) != 0) {
>  		printf("Error - process did not run ok with --no-pci flag\n");
> -		return -1;
> +		goto fail;
>  	}
>  	if (launch_proc(argv2) != 0) {
>  		printf("Error - process did not run ok with -v flag\n");
> -		return -1;
> +		goto fail;
>  	}
>  	if (launch_proc(argv6) != 0) {
>  		printf("Error - process did not run ok with --no-shconf flag\n");
> -		return -1;
> +		goto fail;
>  	}
>  
>  #ifdef RTE_EXEC_ENV_FREEBSD
> @@ -944,73 +969,88 @@ test_misc_flags(void)
>  
>  	if (launch_proc(argv3) != 0) {
>  		printf("Error - process did not run ok with --syslog flag\n");
> -		return -1;
> +		goto fail;
>  	}
>  	if (launch_proc(argv4) == 0) {
>  		printf("Error - process run ok with empty --syslog flag\n");
> -		return -1;
> +		goto fail;
>  	}
>  	if (launch_proc(argv5) == 0) {
>  		printf("Error - process run ok with invalid --syslog flag\n");
> -		return -1;
> +		goto fail;
>  	}
>  	if (launch_proc(argv7) != 0) {
>  		printf("Error - process did not run ok with --huge-dir flag\n");
> -		return -1;
> +		goto fail;
>  	}
>  	if (launch_proc(argv8) == 0) {
>  		printf("Error - process run ok with empty --huge-dir flag\n");
> -		return -1;
> +		goto fail;
>  	}
>  	if (launch_proc(argv9) == 0) {
>  		printf("Error - process run ok with invalid --huge-dir flag\n");
> -		return -1;
> +		goto fail;
>  	}
> -	if (launch_proc(argv10) != 0) {
> -		printf("Error - secondary process did not run ok with invalid --huge-dir flag\n");
> -		return -1;
> +	if (launch_proc(argv10) == 0) {
> +		printf("Error - process run ok with invalid --huge-dir sub-dir flag\n");
> +		goto fail;
>  	}
>  	if (launch_proc(argv11) != 0) {
> -		printf("Error - process did not run ok with --base-virtaddr parameter\n");
> -		return -1;
> +		printf("Error - process did not run ok with --huge-dir subdir flag\n");
> +		goto fail;
>  	}
>  	if (launch_proc(argv12) != 0) {
> +		printf("Error - secondary process did not run ok with invalid --huge-dir flag\n");
> +		goto fail;
> +	}
> +	if (launch_proc(argv13) != 0) {
> +		printf("Error - process did not run ok with --base-virtaddr parameter\n");
> +		goto fail;
> +	}
> +	if (launch_proc(argv14) != 0) {
>  		printf("Error - process did not run ok with "
>  				"--vfio-intr INTx parameter\n");
> -		return -1;
> +		goto fail;
>  	}
> -	if (launch_proc(argv13) != 0) {
> +	if (launch_proc(argv15) != 0) {
>  		printf("Error - process did not run ok with "
>  				"--vfio-intr MSI parameter\n");
> -		return -1;
> +		goto fail;
>  	}
> -	if (launch_proc(argv14) != 0) {
> +	if (launch_proc(argv16) != 0) {
>  		printf("Error - process did not run ok with "
>  				"--vfio-intr MSI-X parameter\n");
> -		return -1;
> +		goto fail;
>  	}
> -	if (launch_proc(argv15) == 0) {
> +	if (launch_proc(argv17) == 0) {
>  		printf("Error - process run ok with "
>  				"--vfio-intr invalid parameter\n");
> -		return -1;
> +		goto fail;
>  	}
> -	if (launch_proc(argv16) != 0) {
> +	if (launch_proc(argv18) != 0) {
>  		printf("Error - process did not run ok with "
>  				"--proc-type as auto parameter\n");
> -		return -1;
> +		goto fail;
>  	}
> -	if (launch_proc(argv17) != 0) {
> +	if (launch_proc(argv19) != 0) {
>  		printf("Error - process did not run ok with "
>  				"--proc-type and --no-shconf parameter\n");
> -		return -1;
> +		goto fail;
>  	}
> -	if (launch_proc(argv18) != 0) {
> +	if (launch_proc(argv20) != 0) {
>  		printf("Error - process did not run ok with "
>  				"--create-uio-dev parameter\n");
> -		return -1;
> +		goto fail;
>  	}
>  
> +	rmdir(hugepath_dir3);
> +	rmdir(hugepath_dir2);
>  	return 0;
> +
> +fail:
> +	rmdir(hugepath_dir3);
> +	rmdir(hugepath_dir2);
> +	return -1;
>  }
>  
>  static int
> diff --git a/doc/guides/linux_gsg/linux_eal_parameters.rst b/doc/guides/linux_gsg/linux_eal_parameters.rst
> index bd3977cb3d..74df2611b5 100644
> --- a/doc/guides/linux_gsg/linux_eal_parameters.rst
> +++ b/doc/guides/linux_gsg/linux_eal_parameters.rst
> @@ -81,7 +81,8 @@ Memory-related options
>  
>  *   ``--huge-dir <path to hugetlbfs directory>``
>  
> -    Use specified hugetlbfs directory instead of autodetected ones.
> +    Use specified hugetlbfs directory instead of autodetected ones. This can be
> +    a sub-directory within a hugetlbfs mountpoint.
>  
>  *   ``--huge-unlink``
>  
> diff --git a/lib/eal/linux/eal_hugepage_info.c b/lib/eal/linux/eal_hugepage_info.c
> index d97792cade..9fb0e968db 100644
> --- a/lib/eal/linux/eal_hugepage_info.c
> +++ b/lib/eal/linux/eal_hugepage_info.c
> @@ -213,10 +213,19 @@ get_hugepage_dir(uint64_t hugepage_sz, char *hugedir, int len)
>  	const size_t pagesize_opt_len = sizeof(pagesize_opt) - 1;
>  	const char split_tok = ' ';
>  	char *splitstr[_FIELDNAME_MAX];
> +	char found[PATH_MAX] = "";
>  	char buf[BUFSIZ];
> -	int retval = -1;
>  	const struct internal_config *internal_conf =
>  		eal_get_internal_configuration();
> +	struct stat st;
> +
> +	/*
> +	 * If the specified dir doesn't exist, we can't match it.
> +	 */
> +	if (internal_conf->hugepage_dir != NULL &&
> +		stat(internal_conf->hugepage_dir, &st) != 0) {
> +		return -1;
> +	}
>  
>  	FILE *fd = fopen(proc_mounts, "r");
>  	if (fd == NULL)
> @@ -226,42 +235,66 @@ get_hugepage_dir(uint64_t hugepage_sz, char *hugedir, int len)
>  		default_size = get_default_hp_size();
>  
>  	while (fgets(buf, sizeof(buf), fd)){
> +		const char *pagesz_str;
> +
>  		if (rte_strsplit(buf, sizeof(buf), splitstr, _FIELDNAME_MAX,
>  				split_tok) != _FIELDNAME_MAX) {
>  			RTE_LOG(ERR, EAL, "Error parsing %s\n", proc_mounts);
>  			break; /* return NULL */
>  		}
>  
> -		/* we have a specified --huge-dir option, only examine that dir */
> -		if (internal_conf->hugepage_dir != NULL &&
> -				strcmp(splitstr[MOUNTPT], internal_conf->hugepage_dir) != 0)
> +		if (strncmp(splitstr[FSTYPE], hugetlbfs_str, htlbfs_str_len) != 0)
>  			continue;
>  
> -		if (strncmp(splitstr[FSTYPE], hugetlbfs_str, htlbfs_str_len) == 0){
> -			const char *pagesz_str = strstr(splitstr[OPTIONS], pagesize_opt);
> +		pagesz_str = strstr(splitstr[OPTIONS], pagesize_opt);
>  
> -			/* if no explicit page size, the default page size is compared */
> -			if (pagesz_str == NULL){
> -				if (hugepage_sz == default_size){
> -					strlcpy(hugedir, splitstr[MOUNTPT], len);
> -					retval = 0;
> -					break;
> -				}
> -			}
> -			/* there is an explicit page size, so check it */
> -			else {
> -				uint64_t pagesz = rte_str_to_size(&pagesz_str[pagesize_opt_len]);
> -				if (pagesz == hugepage_sz) {
> -					strlcpy(hugedir, splitstr[MOUNTPT], len);
> -					retval = 0;
> -					break;
> -				}
> -			}
> -		} /* end if strncmp hugetlbfs */
> +		/* if no explicit page size, the default page size is compared */
> +		if (pagesz_str == NULL) {
> +			if (hugepage_sz != default_size)
> +				continue;
> +		}
> +		/* there is an explicit page size, so check it */
> +		else {
> +			uint64_t pagesz = rte_str_to_size(&pagesz_str[pagesize_opt_len]);
> +			if (pagesz != hugepage_sz)
> +				continue;
> +		}
> +
> +		/*
> +		 * If no --huge-dir option has been given, we're done.
> +		 */
> +		if (internal_conf->hugepage_dir == NULL) {
> +			strlcpy(found, splitstr[MOUNTPT], len);
> +			break;
> +		}
> +
> +		/*
> +		 * Ignore any mount that doesn't contain the --huge-dir
> +		 * directory.
> +		 */
> +		if (strncmp(internal_conf->hugepage_dir, splitstr[MOUNTPT],
> +			strlen(splitstr[MOUNTPT])) != 0) {
> +			continue;
> +		}
> +
> +		/*
> +		 * We found a match, but only prefer it if it's a longer match
> +		 * (so /mnt/1 is preferred over /mnt for matching /mnt/1/2)).
> +		 */
> +		if (strlen(splitstr[MOUNTPT]) > strlen(found))
> +			strlcpy(found, splitstr[MOUNTPT], len);
>  	} /* end while fgets */
>  
>  	fclose(fd);
> -	return retval;
> +
> +	if (found[0] != '\0') {
> +		/* If needed, return the requested dir, not the mount point. */
> +		strlcpy(hugedir, internal_conf->hugepage_dir != NULL ?
> +			internal_conf->hugepage_dir : found, len);
> +		return 0;
> +	}
> +
> +	return -1;
>  }
>  
>  /*